I have to agree with Rod. With the exception of a few older sites that we manage (which we will hopefully upgrade in the future) we have moved on from DNN. Apart from not supporting the latest technologies, there is just too much legacy crap in DNN that makes modern development too hard & too slow. It is just as quick to build most things from scratch using MVC these days & it means that we have the ability to give out customers exactly what they want without being tied down to the old ways of doing things (for example the old membership provider - we are almost in 2017, it's time to move on!).

Now to be fair, this legacy stuff holding developers back is not just related to DNN, it's all CMS's (including WordPress). The amount of old technology you are stuck using, the amount of updates that you have to do etc just is not worth using a CMS these days when you can write stuff extremely quickly using technologies like MVC & Entity Framework.

My suggestion to DNN is to take what you have learnt & start again from scratch using the latest technologies that are going to be around for the next 10 years! I would suggest that you continue to support the current version of DNN for the next few years for current customers, but your main focus NEEDS to be on a modern CMS that is based on modern technologies, not a mish mash of everything like DNN is doing at the moment - as can been seen by the shrinking community, it just does not work.. Pull out asp.net core, create a flexible/modern user manger & page manager that works across all platforms - it's a great start & that's where the future is! 

EDIT: And just one other thing - involve the community when building the new platform. The community is made up of many, many talented people who have great ideas & can contribute great things. Don't separate us by doing what DNN Corp has done at the moment by having things like separate areas/blogs. Respect & start working with the community as we are not the enemy ;)